I've downloaded Robert C Nelson's code and run build_kernel.sh and
install_kernel.sh. I've controlled that sources are patched by rs485 patch.
BBB booted up normally and uname -r says that I am running new kernel. But
I don't have patched kernel headers. I have created serial.h header as
following:
1 #include <linux/types.h>
2
3
4 struct serial_rs485 {
5 __u32 flags; /* RS485 feature flags */
6 #define SER_RS485_ENABLED (1 << 0) /* If enabled */
7 #define SER_RS485_RTS_ON_SEND (1 << 1) /* Logical
level for
8 RTS pin when
9 sending */
10 #define SER_RS485_RTS_AFTER_SEND (1 << 2) /* Logical
level for
11 RTS pin
after sent*/
12 #define SER_RS485_RTS_BEFORE_SEND (1 << 3)
13 #define SER_RS485_USE_GPIO (1 << 5)
14 //#define SER_RS485_RX_DURING_TX (1 << 4)
15 __u32 delay_rts_before_send; /* Delay before send
(milliseconds) */
16 __u32 delay_rts_after_send; /* Delay after send
(milliseconds) */
17 // __u32 padding[5]; /* Memory is cheap, new structs
18 __u32 gpio_pin; /* GPIO Pin Index */
19 __u32 padding[4]; /* Memory is cheap, new structs
20 are a royal PITA .. */
21 };
and used it in small example program:
#include <fcntl.h>
#include <termios.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include "serial.h"
//#include <include/uapi/linux/serial.h>
#include <stdio.h>
#include <unistd.h>
int main()
{
int fd = open("/dev/ttyO4", O_RDWR | O_NOCTTY | O_NDELAY);
if (fd < 0)
{
perror("Error opening tty!");
return 1;
}
struct serial_rs485 rs485conf;
rs485conf.flags |= SER_RS485_ENABLED;
rs485conf.flags |= SER_RS485_USE_GPIO;
rs485conf.gpio_pin = 9;
rs485conf.flags |= SER_RS485_RTS_ON_SEND;
rs485conf.flags &= ~(SER_RS485_RTS_AFTER_SEND);
rs485conf.delay_rts_before_send = 0;
rs485conf.delay_rts_after_send = 0;
if (ioctl (fd, TIOCSRS485, &rs485conf) < 0)
{
perror("Bad ioctl");
}
struct termios ttyc;
tcgetattr(fd, &ttyc);
cfsetospeed(&ttyc, B9600);
cfsetispeed(&ttyc, B9600);
ttyc.c_cflag &= ~CRTSCTS;
ttyc.c_cflag |= CS8 | CLOCAL | CREAD;
ttyc.c_cflag |= CRTSCTS;
ttyc.c_cc[VMIN] = 1;
ttyc.c_cc[VTIME] = 5;
tcsetattr(fd, TCSANOW, &ttyc);
char data = 0xAA;
int i = 0;
while(i < 10000)
{
if(write(fd, &data, 1) < 1)
{
perror("Error sending char");
break;
}
i++;
}
if (close (fd) < 0)
{
perror("Error closing tty!");
return 1;
}
return 0;
}
but RTS pin stays still LOW.
Dne čtvrtek, 4. září 2014 21:51:58 UTC+2 Mickae1 napsal(a):
>
> In the Debian image from Robert C Nelson, the patch rs485 is already
> included.
> Le 4 sept. 2014 20:57, <[email protected] <javascript:>> a écrit :
>
>> Thank you for your answers. The python code is working perfectly.
>> I need to use it in greater C project though. So I am compiling new
>> kernel including RS485 patch. I have tried
>> /opt/scripts/tools/update_kernel.sh hoping that it includes the RS485 patch
>> ...unsuccessfully.
>> I am now following steps from
>> http://jkridner.wordpress.com/2014/06/04/yet-another-set-of-notes-on-building-beaglebone-kernel/
>>
>> Dne středa, 3. září 2014 17:57:53 UTC+2 [email protected] napsal(a):
>>>
>>> Hello,
>>> I'm writing an app for BeagleBoneBlack running debian (3.8.13-bone50). I
>>> would like to use UART4 to communicate with RS485 transmitter over
>>> P9.24(UART4 Tx), P9.26(UART4 Rx) and P8.33 (UART4 RTS).
>>> I've disabled HDMI and enabled overlays BB-UART4 and BB-UART4-RTSCTS
>>>
>>> cat /sys/devices/bone_capemgr.9/slots
>>> 0: 54:PF---
>>> 1: 55:PF---
>>> 2: 56:PF---
>>> 3: 57:PF---
>>> 4: ff:P-O-L Bone-LT-eMMC-2G,00A0,Texas Instrument,BB-BONE-EMMC-2G
>>> 5: ff:P-O-- Bone-Black-HDMI,00A0,Texas Instrument,BB-BONELT-HDMI
>>> 6: ff:P-O-- Bone-Black-HDMIN,00A0,Texas Instrument,BB-BONELT-HDMIN
>>> 7: ff:P-O-L Override Board Name,00A0,Override Manuf,BB-UART4
>>> 10: ff:P-O-L Override Board Name,00A0,Override Manuf,BB-UART4-RTSCTS
>>>
>>> cat /proc/tty/driver/OMAP-SERIAL
>>> serinfo:1.0 driver revision:
>>> 0: uart:OMAP UART0 mmio:0x44E09000 irq:72 tx:345 rx:0 RTS|CTS|DTR|DSR
>>> 4: uart:OMAP UART4 mmio:0x481A8000 irq:45 tx:61355 rx:1 brk:1 RTS|DTR|
>>> DSR
>>>
>>>
>>> RS485 transmitter is connected through RS485-USB converter to PC. When I
>>> run screen /dev/ttyO4 9600 +crtscts and periodicaly write some data to it,
>>> PC receives it properly, but RTS line stays constantly low (I'm using scope
>>> on Tx and RTS lines).
>>> I've also tried to write simple C program, using *struct serial_rs485.
>>> *When
>>> I write some data over this program, I got response: *Resource
>>> temporarily unavailable* and dmesg says
>>> *omap_uart 481a8000.serial: Must use GPIO for RS485 Support. *When I
>>> tried to use:
>>> struct serial_rs485 rs485conf;
>>> rs485conf.flags |= SER_RS485_USE_GPIO;
>>> rs485conf.gpio_pin = GPIO0_9;
>>>
>>> I got error from gcc that it does not know those macros:
>>> ‘SER_RS485_USE_GPIO’ was not declared in this scope
>>> rs485conf.flags |= SER_RS485_USE_GPIO;
>>> ‘struct serial_rs485’ has no member named ‘gpio_pin’
>>> rs485conf.gpio_pin = GPIO0_9;
>>> ‘GPIO0_9’ was not declared in this scope
>>> rs485conf.gpio_pin = GPIO0_9;
>>>
>>> Could somebody help me? I have no more ideas.
>>>
>>>
>>>
>>>
>>>
>>> --
>> For more options, visit http://beagleboard.org/discuss
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>
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